Now Pluto itself seems to be fighting back. Thanks to the Hubble Space Telescope, we’ve learned that Pluto has at least five moons—pretty impressive for something that's supposedly not a planet.
And new research suggests Pluto is just what we were taught long ago: the largest world orbiting the sun beyond Neptune.

In 2005 astronomers discovered Pluto's greatest rival, Eris. It's three times farther from the sun than Pluto. And Eris was thought to be bigger than Pluto, too. But that initial estimate may have been wrong.

We'll find out its exact diameter in July 2015, when NASA's first spacecraft to Pluto zips by. It'll take lots of pictures, probably find more moons and hopefully tell us whether Pluto is indeed the king of the underworld—I mean, of the solar system beyond Neptune.